1. Field of the Invention
This invention pertains to electric generators, and more particularly to the mechanical construction of generators used on engine-driven welding machines.
2. Description of the Prior Art
In portable engine-driven welding machines, an internal combustion engine provides the mechanical power to rotate a generator. In turn, the generator creates electric power for operating the numerous electrical components that enable welding to take place.
To effectively and economically serve its purpose, a welding machine generator must fulfill several requirements. It must be rigidly stationary with respect to the engine. It must be well cooled. Ideally, its cooling system should also cool the various other welding-related components inside the welding machine. For economy purposes, it is highly desirable that different engines can be used in a welding machine with minimum alterations to the generator.
Generators used in prior engine-driven welding machines were typically constructed with two end housings and a steel barrel captured between them. The generator stator was secured to the barrel. In some prior generators, the barrel was designed to produce parallel cooling air flow paths inside the welding machine. One path was through the stator of the generator to cool it. Another path was mostly outside the generator to cool the welding-related electrical components inside the welding machine but outside the generator.
Factors that detrimentally affected prior generator performance, even during normal operation, included unequal thermal expansion of the generator components. For example, to minimize generator weight, the end housings were frequently made of aluminum. Since the aluminum end housings and the steel stator and barrel expanded at different rates with temperature, there was a tendency to develop excessive thermal stresses. In addition, prior generators suffered from the disadvantage of being limited to mounting to only a single internal combustion engine. The three-piece construction of two end housings plus a barrel was also undesirably expensive and difficult to assemble.
Thus, further development of welding machine generators is desirable.